1. Field
Exemplary embodiments relate to an optical mask. More particularly, exemplary embodiments relate to an optical mask including a light-transmitting base substrate; a first reflective pattern layer which is formed on the light-transmitting base substrate and includes a first opening portion transmitting light emitted from under the light-transmitting base substrate and a first reflective portion reflecting the light; and a second reflective pattern layer which is formed over the first reflective pattern layer.
2. Discussion of the Background
Generally, an organic electroluminescent device includes an anode, a cathode and organic layers interposed between the anode and the cathode. The organic layers include at least an organic light-emitting layer and may further include a hole injection layer, a hole transport layer, an electron transport layer and an electron injection layer. The organic electroluminescent device is classified as a polymer organic electroluminescent device or a low molecular weight organic electroluminescent device according to the material that forms the organic light-emitting layer.
To implement a full-color organic electroluminescent device, the organic light-emitting layer should be patterned. An organic light-emitting layer in a low molecular weight organic electroluminescent device may be patterned using a fine metal mask, and an organic light-emitting layer in a polymer organic electroluminescent device may be patterned using an inkjet printing method or a laser induced thermal imaging (LITI) method.
In particular, the LITI method has the advantage of finely patterning the above organic layer. Also, the LITI method is a dry process, whereas the inkjet printing method is a wet process.
Forming a polymer organic layer pattern using the LITI method requires at least a light source and organic electroluminescent device substrates, i.e., a device substrate (or a target substrate) and a transfer substrate. The transfer substrate consists of a base film, a light-to-heat conversion layer, and a transfer layer composed of one or more organic layers.
The organic layers of the transfer substrate may be transferred to the device substrate as described hereinafter: Light emitted from the light source is absorbed; The light is converted into thermal energy by the light-to-heat conversion layer of the transfer substrate; The organic layers of the transfer substrate are evaporated by the thermal energy; The organic layer is transferred onto the device substrate from the transfer substrate.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the inventive concept, and, therefore, it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.